This proposal is directed to the assessment of the therapeutic efficacy of co-administration of caffeine with amphetamine by employing the continuous performance task (CPT) as an objective measure of hyperkinesis in children. Diagnosed hyperkinetic children will be compared with non-hyperkinetic children on the CPT prior to drug treatment in order to establish this test as an accurate measurement of the attention disorder deficit that characterizes the hyperkinetic syndrome. Subsequently, a multiple exposure crossover design will be used to test the therapeutic efficacy of caffeine administration with lowered doses of Dexedrine, as compared to placebo-high dose Dexedrine and placebo-low dose Dexedrine in the control of hyperkinesis. Subjective parental and clinical reports will be evaluated and compared with multiple CPT tests to analyse the correlation between measurements throughout the 12-week course of drug treatment. If caffeine co-administration with lowered doses of Dexedrine does not compromise the effective treatment of hyperkinesis, this regimen can be employed to preclude the reported adverse side effects of chronic stimulant use.